Preheat the oven to 350 degrees F (175 degrees C).

Pull out any salmon bones with pliers. Slice salmon into 5 equal portions. Place salmon skin side-down on a sheet of aluminum foil. Transfer to a large baking pan. Season salmon with salt and pepper; loosely cover with foil.

Bake in the preheated oven for 10 minutes.

Remove baking pan from oven and uncover. Smear pesto over each portion of salmon. Sprinkle with Parmesan cheese. Continue baking, uncovered, until cheese is melted, about 10 minutes.

Whisk butter and lemon juice together in a small bowl. Drizzle over salmon.